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Academic literature on the topic 'Disulfide bonds'

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Published: 4 June 2021
Last updated: 27 April 2022

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Journal articles on the topic "Disulfide bonds"

1

Hogg, Philip J. "Allosteric Disulfide Bonds in Thrombosis and Thrombolysis." Blood 108, no. 11 (November 16, 2006): 4036. http://dx.doi.org/10.1182/blood.v108.11.4036.4036.

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Abstract Allosteric disulfide bonds control protein function by mediating conformational change when they undergo reduction or oxidation. The known allosteric disulfides are characterized by a particular bond geometry, the -RHStaple. A number of thrombosis and thrombolysis proteins contain one or more disulfide bonds of this type. Tissue factor (TF) is the first haemostasis protein shown to be controlled by an allosteric disulfide, the Cys186-Cys209 bond in the membrane-proximal fibronectin type III domain. TF exists in three forms on the cell surface; a cryptic form that is inert, a coagulant form that binds factor VIIa to initiate coagulation, or a signaling form that binds VIIa and cleaves protease activated receptor 2 that functions in inflammation, tumor progression and angiogenesis. Reduction and oxidation of the Cys186-Cys209 bond is central to the transition between the three activities of TF. The redox state of the bond appears to be controlled by protein disulphide isomerase and NO. Plasmin(ogen), vitronectin, glycoprotein 1balpha, integrin beta3 and thrombomodulin also contain -RHStaple disulfides and there is circumstantial evidence that the function of these proteins may involve redox change of these disulfide bonds.
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Pijning, Aster E., Joyce Chiu, Reichelle X. Yeo, Jason W. H. Wong, and Philip J. Hogg. "Identification of allosteric disulfides from labile bonds in X-ray structures." Royal Society Open Science 5, no. 2 (February 2018): 171058. http://dx.doi.org/10.1098/rsos.171058.

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Protein disulfide bonds link pairs of cysteine sulfur atoms and are either structural or functional motifs. The allosteric disulfides control the function of the protein in which they reside when cleaved or formed. Here, we identify potential allosteric disulfides in all Protein Data Bank X-ray structures from bonds that are present in some molecules of a protein crystal but absent in others, or present in some structures of a protein but absent in others. We reasoned that the labile nature of these disulfides signifies a propensity for cleavage and so possible allosteric regulation of the protein in which the bond resides. A total of 511 labile disulfide bonds were identified. The labile disulfides are more stressed than the average bond, being characterized by high average torsional strain and stretching of the sulfur–sulfur bond and neighbouring bond angles. This pre-stress likely underpins their susceptibility to cleavage. The coagulation, complement and oxygen-sensing hypoxia inducible factor-1 pathways, which are known or have been suggested to be regulated by allosteric disulfides, are enriched in proteins containing labile disulfides. The identification of labile disulfide bonds will facilitate the study of this post-translational modification.
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Schmidt, Bryan, Lorraine Ho, and Philip J. Hogg. "Allosteric Disulfide Bonds†." Biochemistry 45, no. 24 (June 2006): 7429–33. http://dx.doi.org/10.1021/bi0603064.

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Glidewell, Christopher, John N. Low, and James L. Wardell. "Conformational preferences and supramolecular aggregation in 2-nitrophenylthiolates: disulfides and thiosulfonates." Acta Crystallographica Section B Structural Science 56, no. 5 (October 1, 2000): 893–905. http://dx.doi.org/10.1107/s0108768100007114.

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In each of the asymmetrically substituted disulfides 2-nitro-4′-methyldiphenyl disulfide, C13H11NO2S2 (1), 2-nitro-4′-chlorodiphenyl disulfide, C12H8ClNO2S2 (2), 2,4-dinitro-4′-methyldiphenyl disulfide, C13H10N2O4S2 (3), and 2,4-dinitrophenyl-2′-methoxycarbonylmethyl disulfide, C9H8N2O6S2 (4), and in both of the symmetrically substituted disulfides bis(2-nitrophenyl) disulfide, C12H8N2O4S2 (5), and bis(2-nitro-4-trifluoromethylphenyl) disulfide, C14H6F6N2O4S2 (6), the 2-nitro groups are essentially coplanar with the adjacent aryl ring and the S atom remote from the nitrated aryl ring is also essentially coplanar and transoid to the nitro group. In S-(2-nitrophenyl) 2-nitrobenzene thiosulfonate, C12H8N2O6S2 (7), which contains three independent molecules in the asymmetric unit, all six of the independent nitro groups are twisted out of the plane of the adjacent aryl rings. The crystal structures of (1)–(3) contain isolated molecules, that of (4) contains centrosymmetric dimers held together by C—H...O hydrogen bonds, while in the structures of (5)—(7), respectively, the C—H...O hydrogen bonds generate one-, two- and three-dimensional arrays. The interplay between molecular conformation and supramolecular aggregation is discussed.
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Liu, Tao, Yan Wang, Xiaozhou Luo, Jack Li, Sean A. Reed, Han Xiao, Travis S. Young, and Peter G. Schultz. "Enhancing protein stability with extended disulfide bonds." Proceedings of the National Academy of Sciences 113, no. 21 (May 9, 2016): 5910–15. http://dx.doi.org/10.1073/pnas.1605363113.

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Disulfide bonds play an important role in protein folding and stability. However, the cross-linking of sites within proteins by cysteine disulfides has significant distance and dihedral angle constraints. Here we report the genetic encoding of noncanonical amino acids containing long side-chain thiols that are readily incorporated into both bacterial and mammalian proteins in good yields and with excellent fidelity. These amino acids can pair with cysteines to afford extended disulfide bonds and allow cross-linking of more distant sites and distinct domains of proteins. To demonstrate this notion, we preformed growth-based selection experiments at nonpermissive temperatures using a library of random β-lactamase mutants containing these noncanonical amino acids. A mutant enzyme that is cross-linked by one such extended disulfide bond and is stabilized by ∼9 °C was identified. This result indicates that an expanded set of building blocks beyond the canonical 20 amino acids can lead to proteins with improved properties by unique mechanisms, distinct from those possible through conventional mutagenesis schemes.
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Onda, Yayoi. "Oxidative Protein-Folding Systems in Plant Cells." International Journal of Cell Biology 2013 (2013): 1–15. http://dx.doi.org/10.1155/2013/585431.

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Plants are unique among eukaryotes in having evolved organelles: the protein storage vacuole, protein body, and chloroplast. Disulfide transfer pathways that function in the endoplasmic reticulum (ER) and chloroplasts of plants play critical roles in the development of protein storage organelles and the biogenesis of chloroplasts, respectively. Disulfide bond formation requires the cooperative function of disulfide-generating enzymes (e.g., ER oxidoreductase 1), which generate disulfide bonds de novo, and disulfide carrier proteins (e.g., protein disulfide isomerase), which transfer disulfides to substrates by means of thiol-disulfide exchange reactions. Selective molecular communication between disulfide-generating enzymes and disulfide carrier proteins, which reflects the molecular and structural diversity of disulfide carrier proteins, is key to the efficient transfer of disulfides to specific sets of substrates. This review focuses on recent advances in our understanding of the mechanisms and functions of the various disulfide transfer pathways involved in oxidative protein folding in the ER, chloroplasts, and mitochondria of plants.
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Saunders, Aleister J., Gregory B. Young, and Gary J. Pielak. "Polarity of disulfide bonds." Protein Science 2, no. 7 (July 1993): 1183–84. http://dx.doi.org/10.1002/pro.5560020713.

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Robinson, Philip J., Shingo Kanemura, Xiaofei Cao, and Neil J. Bulleid. "Protein secondary structure determines the temporal relationship between folding and disulfide formation." Journal of Biological Chemistry 295, no. 8 (January 17, 2020): 2438–48. http://dx.doi.org/10.1074/jbc.ra119.011983.

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How and when disulfide bonds form in proteins relative to the stage of their folding is a fundamental question in cell biology. Two models describe this relationship: the folded precursor model, in which a nascent structure forms before disulfides do, and the quasi-stochastic model, where disulfides form prior to folding. Here we investigated oxidative folding of three structurally diverse substrates, β2-microglobulin, prolactin, and the disintegrin domain of ADAM metallopeptidase domain 10 (ADAM10), to understand how these mechanisms apply in a cellular context. We used a eukaryotic cell-free translation system in which we could identify disulfide isomers in stalled translation intermediates to characterize the timing of disulfide formation relative to translocation into the endoplasmic reticulum and the presence of non-native disulfides. Our results indicate that in a domain lacking secondary structure, disulfides form before conformational folding through a process prone to nonnative disulfide formation, whereas in proteins with defined secondary structure, native disulfide formation occurs after partial folding. These findings reveal that the nascent protein structure promotes correct disulfide formation during cotranslational folding.
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van Anken, Eelco, Rogier W. Sanders, I. Marije Liscaljet, Aafke Land, Ilja Bontjer, Sonja Tillemans, Alexey A. Nabatov, William A. Paxton, Ben Berkhout, and Ineke Braakman. "Only Five of 10 Strictly Conserved Disulfide Bonds Are Essential for Folding and Eight for Function of the HIV-1 Envelope Glycoprotein." Molecular Biology of the Cell 19, no. 10 (October 2008): 4298–309. http://dx.doi.org/10.1091/mbc.e07-12-1282.

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Protein folding in the endoplasmic reticulum goes hand in hand with disulfide bond formation, and disulfide bonds are considered key structural elements for a protein's folding and function. We used the HIV-1 Envelope glycoprotein to examine in detail the importance of its 10 completely conserved disulfide bonds. We systematically mutated the cysteines in its ectodomain, assayed the mutants for oxidative folding, transport, and incorporation into the virus, and tested fitness of mutant viruses. We found that the protein was remarkably tolerant toward manipulation of its disulfide-bonded structure. Five of 10 disulfide bonds were dispensable for folding. Two of these were even expendable for viral replication in cell culture, indicating that the relevance of these disulfide bonds becomes manifest only during natural infection. Our findings refine old paradigms on the importance of disulfide bonds for proteins.
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Haworth, Naomi L., and Merridee A. Wouters. "Cross-strand disulfides in the non-hydrogen bonding site of antiparallel β-sheet (aCSDns): poised for biological switching." RSC Advances 5, no. 105 (2015): 86303–21. http://dx.doi.org/10.1039/c5ra10672a.

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aCSDns are forbidden disulfides with protein redox-activity. Within the aCSDn structural motif, a cognate substrate of Trx-like enzymes, the disulfide bonds are strained and metastable, facilitating their role as redox-regulated protein switches.
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Dissertations / Theses on the topic "Disulfide bonds"

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Schumacher, F. F. "Functional bridging of protein disulfide bonds with maleimides." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1382399/.

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The application of chemical methods to biological systems has led to great advances in all life sciences and the discovery of novel approaches for therapy and diagnosis. Pivotal amongst these methods is the ability to chemically modify proteins to enhance their biophysical properties or add new functionality. Despite the success, the chemical toolbox of efficient and widely applicable protocols is relatively limited. In the work presented in this thesis the idea of protein modification via the targeting of solvent accessible disulfide bonds is explored. These are fairly common in secreted proteins and their reduction affords two cysteine residues, which are highly reactive nucleophiles. However, to preserve their native function – stabilisation and maintenance of the protein structure – ideally bis-reactive compounds are used that react simultaneously with both thiols and keep the covalent connection of the disulfide bond intact. To this end a selection of maleimides substituted with good leaving groups in the 3 and 4 positions as well as their N-functionalised versions were synthesised and tested for their reactivity. The findings were transferred to the small peptide hormone somatostatin, which served as a model system to explore kinetics and feasibility of the proposed “functionalisation by bridging”. Changing the leaving groups from halides to thiols enabled the development of in situ protocols where the bridging reagent could be employed in tandem with the reducing agent, greatly decreasing the reaction time and unwanted side reactions such as dimerisation or unfolding. The developed methods were then utilised to bridge the cystines of insulin as well as a selection of full length antibodies and antibody fragments. PEGylated, biotinylated, fluorescent or spin labelled analogues of these proteins were also synthesised. The biological activity, stability and functionality of the conjugates were assessed in biochemical and biophysical assays. Overall the functionalisation of disulfide bonds with maleimides was found to be site-specific, fast, high yielding and the inserted bridge was stable under various conditions. The modification was well tolerated and all prepared analogues exhibited the desired functionality. The scope and potential of present and future applications of the method are discussed.
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Eklund, Aron Charles 1974. "Patterns in the sequence context of protein disulfide bonds." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16804.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Biology, February 2002.
Includes bibliographical references (leaves 60-62).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Disulfide bonds play an important role in the structural stability of the proteins that contain them. Yet, little is known about the specificity with which they are formed. To address this, a representative set of disulfide bonds from nonhomologous eukaryotic polypeptides was created. The amino acid sequences flanking these disulfide bonds were searched for conserved patterns that may reflect recognition sites by the disulfide bond forming enzyme protein disulfide isomerase (PDI). Several methods of classifying disulfide bonds were explored, and each class was analyzed for conserved sequence patterns. To maximize the chances of finding a conserved recognition site, a simulated annealing algorithm was implemented to divide a set of disulfide-bonded cysteines into two sets of cysteines with an average sequence environment that is as far from randomly-distributed as possible. No significant conserved patterns were found in the set of disulfide bonds or within any of the classification schemes introduced. Additionally, several methods for predicting disulfide bond connectivity were explored. The most successful methods predicted connectivity based on the sequential distance between cysteines.
by Aron Charles Eklund.
S.M.
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Baldus, Ilona Beatrice [Verfasser], and Peter [Akademischer Betreuer] Comba. "Mechanochemistry of Disulfide Bonds in Proteins / Ilona Beatrice Baldus ; Betreuer: Peter Comba." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177040786/34.

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Bracchi, Michael Edward. "Exploring the orthogonal dynamic covalent imine and disulfide bonds in polymer systems." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3989.

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In the field of supramolecular systems chemistry the desire of researchers to endow functional macromolecular systems with orthogonal stimuli-responsiveness has fueled interest in the incorporation of multiple orthogonal dynamic covalent chemistries within a single chemical system. Dynamic covalent chemistry involves reversible bond forming processes which can be harnessed in the development of dynamic supramolecular systems providing a mechanism for structural reconfiguration of system components in response to external stimuli. Despite the inspiring gamut of recently brandished studies, there is a still a call on the resourcefulness of chemists to expand the capacity for the introduction of multi-faceted, orthogonal, stimuli-responsive behaviors. Herein, a critical analysis of recently reported landmark studies has been undertaken wherein the utility of orthogonal dynamic covalent bonding motifs in functional systems is highlighted. Furthering the concepts of orthogonality with respect to dynamic covalent chemistry presented therein, a small molecule ‘model system’ was developed with which the orthogonality of imine and disulfide dynamic covalent bonds was demonstrated by its operation. A key focus of this preliminary work was the orthogonal bond forming and bond breaking processes of imine and disulfide dynamic covalent bonds. Upon the establishment of conditions necessary to exploit the orthogonal utility of imine and disulfide bonds, the incorporation of aldehydes, amines and thiols within acrylamide-based copolymers as pendant functional groups was achieved. These pre-formed functional polymer building blocks were shown to undergo stimuli-responsive intermolecular cross-linking in aqueous media yielding disulfide or imine cross-linked nanoparticles or hydrogels. The scope and utility of imine and disulfide bonds in the formation of these nanostructured materials is compared and contrasted. It is reasoned that expanding understanding and availability of dynamic covalent bonding motifs will facilitate evolution of systems of greater sophistication capable of embodying increasingly information-rich processes.
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Merkel, Brian J. "Characterization of fibroblasts with a unique defect in processing antigens with disulfide bonds." VCU Scholars Compass, 1994. http://scholarscompass.vcu.edu/etd/5076.

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A Chinese hamster ovary (CHO) fibroblast, transfected with murine major histocompatibility complex (MHC) class II genes, inefficiently simulated CD4+ Th cells specific for ovalbumin (OVA), hen egg lysozyme (HEL), and pork insulin which contains disulfide bonds. However, the fibroblasts elicited a T cell response to λ-repressor, which lacks disulfide bonds, and efficiently presented synthetic peptides. A somatic cell hybrid WALC, generated by fusing the hamster fibroblast with a murine L cell fibroblast, very efficiently processed OVA and HEL, suggesting that impaired processing was genetically complemented, suggesting that the processing defect is a recessive trait. Three distinct processing phenotypes were observed among twenty-eight hybrid clones analyzed for their ability to process a suboptimal concentration of OVA suggesting that a limited number of genes mediates the defect of WAB4 cells. The hamster fibroblasts were capable of processing two distinct denatured forms of OVA and carboxymethylated HEL either as effectively or more efficiently than a B lymphoma cell. The CHO cells also displayed diminished disulfide reduction of an endocytosed conjugate consisting of 125I-tyramine linked to poly-(D-lysine) through a disulfide spacer compared with that of the cell hybrid, providing direct evidence for defective reductive cleavage for the CHO cells. Diminished aspartic acid-mediated proteolysis of Ag could not account for the phenotype, because cell lysates and separated organelles from the fibroblast possessed higher acidic aspartyl proteolytic activity than lysates and organelles from a B lymphoma cell. The WAB4 cells had normal intracellular levels of cysteine, however they possessed diminished levels of intracellular glutathione (GSH). Buthionine sulfoximine (BSO) - mediated reduction of intracellular levels of GSH decreased the ability of the hybrid line WALC to process HEL. Conversely, treatment of WAB4 cells with N-acetyl cysteine increased their efficiency in the processing of HEl. These findings indicate that the intracellular level of GSH influences the capacity of cells to process antigens with the disulfide bonds. Thus, the antigen processing defect exhibited by transfected CHO cells is probably caused by their impaired ability to reduce disulfide bonds which may be related to the diminished intracellular GSH level.
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Bewley, Kathryn Duffy. "Characterization of electron-transfer proteins: archaeal disulfide bonds and bacterial multi-heme cytochromes c." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12715.

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Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Electron-transfer proteins that are responsible for redox homeostasis and long. range electron transfer are vital to intracellular and extracellular processes. In this thesis, several examples of electron-transfer proteins are studied in order to determine the emergent properties of multi-electron transfer chemistry. Thioredoxin (Trx) is a small redox-active protein that functions via its disulfide bond. These disulfides, characterized by a CXXC motif, are found to have a range of redox potentials that are often linked to function. Chapter 2 uses a set of archaeal thioredoxins from Thermoplasma acidophilum and Archaeoglobus fulgidus to test the current hypotheses using protein film voltammetry and solution-based experiments that examine folding energies. Thioredoxin reductase (TrxR) functions to provide reducing equivalents to Trx to keep it active in the cell. The TrxR from Thermoplasma acidophilum has been noted to be unusual in that it does not use NADPH as a reductant, as found in most TrxRs. The reaction between T. acidophilum Trx and TrxR is explored in Chapter 3 and a bioinfonnatic analysis of TaTrxR is included in Chapter 4 to better understand its relationship in the TrxR protein family, as well as attempt to identity its native reductant. In Chapter 5, the periplasmic decaheme cytochrome DmsE from Shewanella oneidensis is biochemically characterized. This protein is part of the dimethyl sulfoxide reduction pathway and is compared with MtrA, the well-studied decaheme protein from the dissimilatory metal reduction pathway in Shewanella. Additionally, a Cytoscape analysis of the MtrA/DmsE and OmcA protein families is presented. Finally, Chapter 6 explores the electrochemical properties of two multi-heme proteins from Nitrosomonas europaea: cytochrome c554 and hydroxylamine oxidoreductase (HAO). Cytochrome c554, a tetraheme cytochrome, has been shown to have cooperativity between two of its heme groups and gating has been. observed in protein film voltammetry (PFV) experiments. This gating is further explored in this Chapter. The enzymatic hydroxylamine reduction by HAO, a reverse reaction, is also presented.
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Rosenthal-Kim, Emily Quinn. "Green Polymer Chemistry: Synthesis of Poly(disulfide) Polymers and Networks." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386525065.

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Utter, Bryan David. "PHEROMONE-INTERACTING REPLICATION PROTEIN CONTROLS ENTEROCOCCAL CONJUGATIVE PLASMID HOST RANGE AND STABILITY THROUGH DISULFIDE BONDS." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/211277.

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Microbiology and Immunology
Ph.D.
Enterococci are found in soil, sewage, food, water, and are commensal to the gastrointestinal tracts of mammals, insects, and birds. Enterococci often become nosocomial pathogens that cause a wide variety of diseases including urinary tract infections, endocarditis, and septicemia. These infections are often difficult to treat with antibiotics because most of the nosocomial strains are multi-drug resistant. Enterococcal plasmids function as reservoirs for resistance genes because they are extremely stable, allow for specific and efficient transfer, and can acquire resistance determinants from the chromosome and other plasmids. Additionally, enterococcal plasmids transfer across species boundaries transferring resistance genes like vancomycin to species like Staphylococcus aureus. There are two types of enterococcal plasmids, pheromone-responsive and broad host range. Pheromone-responsive plasmids are extremely stable, have a limited host range, and are primarily found in Enterococcus faecalis. Broad host range plasmids of E. faecalis and Enterococcus faecium are less stable than pheromone-responsive plasmids, but have an expanded host range into other Gram-positive species. E. faecalis has at least 25 known pheromone-responsive conjugative plasmids. One of the most extensively studied pheromone-responsive conjugative plasmids, pCF10. Conjugation of pCF10 from donor to recipient cell is induced by pheromone cCF10. cCF10 is contained within n the lipoprotein signal sequence encoded by the E. faecalis chromosomal gene ccfA. The lipoprotein signal sequence is processed by a series of proteolytic cleavage events to produce mature cCF10. Maturation of pheromone cCF10 produces three peptides: pre-cCF10 (CcfA1-22), cCF10 (CcfA13-19), and CcfA1-12. Cells containing pCF10 continue to produce cell membrane associated precursor pheromone of cCF10 (pre-cCF10), as well as, secreted and cell wall-associated cCF10. The presence of cCF10 does not self-induce conjugation by the donor cell because of two inhibitory molecules, PrgY and iCF10. Transmembrane protein PrgY is encoded by pCF10 and reduces cell wall associated cCF10, iCF10 is a pCF10 encoded inhibitory peptide (AITLIFI) that binds to PrgX, preventing cCF10 binding. While cCF10 controls pCF10 conjugation, pre-cCF10 controls host range of pCF10 by interacting with pCF10 replication initiation protein PrgW. cCF10 can initiate conjugation and mobilize the transfer of plasmids into other species, including Lactococcus lactis, but pCF10 cannot be maintained within the cell. However, if L. lactis is engineered to produce pre-cCF10, pCF10 can be maintained. The pre-cCF10 involvement in the establishment of pCF10 into other species might be related to the observation that it binds to the pCF10 replication initiation protein PrgW. By in vitro affinity chromatography experiments, interaction of cCF10 and pre-cCF10 with PrgW induced changes in PrgW mobility in gel electrophoresis that caused by formation of doublets and formation of aggregates which were thought to be mediated by disulfide bonds. Initial evidence of regulation of PrgW conformation by disulfide bonds was seen in Western blots of E. faecalis whole cell lysates where PrgW migration is sensitive to reduction. Sequence alignment comparisons between PrgW and a group of 54 of 59 known RepA_N superfamily proteins in E. faecalis revealed three highly conserved cysteines; these RepA_N proteins had a limited host range to E. faecalis. To study the importance of theses cysteines in pCF10 maintenance and host range limitation, prgW single, double, and triple cysteine to alanine (C to A) substitutions were generated. The cysteine mutant prgW was cloned into a plasmid functioning as either a contained the prgW alone (pORI10), or containing prgW with genes necessary for efficient pCF10 maintenance (pMSP6050). While all cysteine mutant plasmids of pORI10 and pMSP6050 were still capable of replicating in E. faecalis, the plasmid stability and copy number decreased, providing evidence that the cysteines were important to PrgW function. Additionally, Western blot analysis revealed PrgW C to A substitutions decreased PrgW aggregation. Mutations of PrgW cysteines reduced pMSP6050 stability and aggregation, but increased host range to L. lactis. Both L. lactis engineered to produce pre-cCF10 and the mutation of the conserved cysteines of PrgW extended host range of pMSP6050 into L. lactis. These data taken together with the observations that pre-cCF10 induced PrgW aggregation suggested that pre-cCF10 regulated the activity of the PrgW replication initiation protein through disulfide bonds. While the conserved cysteines of RepA_N proteins are found only in E. faecalis, phylogenetic analysis revealed that RepA_N homologs lacking the three cysteines are also found in E. faecium or S. aureus, suggesting that the host range of multiple plasmids might be affected by cysteine bond formation. Phylogenetic analysis also showed that the RepA_N proteins of enterococci and staphylococci appear to have evolved to determine host range based on the presence of two of the three conserved cysteines. Modular evolution of E. faecalis plasmids, like pCF10, that contained RepA_N proteins with three conserved cysteines, might have determined the fate of the plasmid as a limited host range, stable reservoir for antibiotic resistance.
Temple University--Theses
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Ogawa, Nozomi. "Resolving Disulfide Bond Patterns in SNAP25B Cysteine-Rich Region using LC Mass Spectrometry." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3651.

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A global analysis of the human proteome demonstrates that there are ~5500 tryptic fragments that contain four cysteines in close proximity. Elucidating whether they form disulfide bonds in vivo under different conditions is particularly important because cysteines are known to be a vital cellular redox sensor as well as a catalytic site for important biochemical reactions. However, currently there are no methods that can resolve disulfide patterns in closely-packed cysteine residues from a complex sample. In order to address this problem, we have developed a novel mass-spectrometry-based method to identify the different disulfide bonding patterns possible, using SNAP25B cysteine-rich region as a test case. Unlike traditional proteomics, this method uses non-reduced sample preparation, thus preserving intact disulfide bonds. It relies on collision-induced dissociation (CID) to cause double-backbone and heterolytic disulfide-bond cleavage and compares this to the theoretical MS/MS spectra. CID in an ion trap gives robust detection of double backbone cleavages and heterolytic disulfide-bond cleavages. Here, we report, for the first time, identification of all three disulfide patterns for double-disulfide species of SNAP25B using collision-induced dissociation.
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Briggs, David Blaine. "BIOCHEMICAL CHARACTERIZATION OF ADIPONECTIN OLIGOMERIZATION." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145741.

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Adiponectin, a hormone that homo-oligomerizes into trimer, hexamer, or higher molecular weight (HMW) species, is involved in maintaining insulin sensitivity in muscle and liver. Interestingly, its functions appear to be oligomer-specific. Recent data suggest that HMW levels are decreased in obesity and insulin resistance, although, the cause for this decrease is not known. Impaired assembly to the octadecamer represents one possible reason for decreased HMW adiponectin in insulin resistance and type 2 diabetes, but mechanisms by which HMW adiponectin assembles are unknown. This dissertation discusses the progress that we have made regarding formation of HMW adiponectin in vitro.I found that disulfide bonds are important in the assembly process to octadecameric adiponectin, but are not required for stability of the octadecamer itself. We showed that hydrogen peroxide accelerated oligomerization to the octadecamer through formation of disulfide bonds, while alkylation of the cysteines led to inhibition of both oligomerization and disulfide bond formation. Using comparative native/denaturing polyacrylamide gel electrophoresis (PAGE), dynamic light scattering, and tandem mass spectrometry, we demonstrated that octadecamer is stable in the absence of disulfide bonds by using multiple biochemical and biophysical assays. In addition, oxidized adiponectin oligomerizes to octadecamer far slower than reduced adiponectin. To further evaluate the role of disulfide bonds in the formation to octadecamer, we analyzed the role of reduction potential on adiponectin oligomerization. We observed that under immediate oxidizing conditions, hexamers and trimers form. Oxidized hexamer can form HMW adiponectin through disulfide bond rearrangement using beta-mercaptoethanol (βME) or increasing the total concentration of glutathione under oxidizing conditions. To further understand the role of disulfide bonds, we showed that zinc increased the oligomerization to octadecamer. This effect was associated with decreased initial disulfide bonding during the assembly to the octadecamer. In summary, these data suggest the rate of disulfide bond formation and the ability to undergo disulfide bond isomerization are important in the oligomerization process of HMW adiponectin.
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Books on the topic "Disulfide bonds"

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Nagradova, N. K. Foldases catalyzing the formation and isomerization of disulfide bonds in proteins. New York: Nova Biomedical Books, 2009.

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Nagradova, N. K. Foldases catalyzing the formation and isomerization of disulfide bonds in proteins. New York: Nova Biomedical Books, 2009.

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Koivu, Juha. Protein disulphide isomerase and disulphide bond formation in collagen biosynthesis. Oulu: University of Oulu, 1987.

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Vincent-Sealy, Lois V. Investigation of the role of disulfide bond formation in the secretion and activity of virulence factors in Erwinia carotovora subspecies carotovora. [s.l.]: typescript, 1997.

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Grant, Gregory A., ed. Synthetic Peptides. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195132618.001.0001.

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The first synthetic peptides were produced a century ago. In the ensuing period, they have developed as valuable research tools that are readily available to all researchers. However, since most researchers do not make their own peptides, they are often unfamiliar with not only the synthetic chemistry but also with important and useful aspects of design, analysis, handling, and applications. This volume is the second edition of a volume that was first published 10 years ago. It is written by experts in the field who provide detailed descriptions as well as practical advice for producing and using synthetic peptides. The various chapters cover peptide design considerations, the synthetic chemistry, the evaluation of the synthetic product, and the modern applications of synthetic peptides. This includes the basic principles of peptide structure, analysis and chain assembly as well as the latest in selective disulfide bond formation, new strategies for the production of large peptides, and sequencing peptides by mass spectrometry. This book was designed with the intent of providing useful information both for the novices to the field as well as more seasoned practitioners. Its contents will help prevent problems commonly encountered and allow scientists to optimize their use of synthetic peptides.
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Book chapters on the topic "Disulfide bonds"

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Wong, Jason W. H., and Philip J. Hogg. "Allosteric Disulfide Bonds." In Folding of Disulfide Proteins, 151–82. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-7273-6_8.

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Pijning, Aster E., and Philip J. Hogg. "CHAPTER 2.3. Allosteric Disulfide Bonds." In Oxidative Folding of Proteins, 152–74. Cambridge: Royal Society of Chemistry, 2018. http://dx.doi.org/10.1039/9781788013253-00152.

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Shabanpoor, Fazel, Mohammed Akhter Hossain, Feng Lin, and John D. Wade. "Sequential Formation of Regioselective Disulfide Bonds in Synthetic Peptides with Multiple Disulfide Bonds." In Methods in Molecular Biology, 81–87. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-544-6_5.

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Hlavácek, J., J. Konvalinka, J. Slaninova, and I. Frič. "OXYTOCIN ANALOGS CONTAINING TWO DISULFIDE BONDS." In Porto Carras, Chalkidiki, Greece, Aug. 31–Sept. 5, 1986, edited by Dimitrios Theodoropoulos, 497–500. Berlin, Boston: De Gruyter, 1987. http://dx.doi.org/10.1515/9783110864243-116.

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Aitken, Alastair, and Michèle Learmonth. "Estimation of Disulfide Bonds Using Ellman’s Reagent." In Springer Protocols Handbooks, 487–88. Totowa, NJ: Humana Press, 1996. http://dx.doi.org/10.1007/978-1-60327-259-9_82.

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Aitken, Alastair, and Michèle Learmonth. "Estimation of Disulfide Bonds Using Ellman’s Reagent." In Springer Protocols Handbooks, 1053–55. Totowa, NJ: Humana Press, 2009. http://dx.doi.org/10.1007/978-1-59745-198-7_114.

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Schönfelder, Jörg, Alvaro Alonso-Caballero, and Raul Perez-Jimenez. "Mechanochemical Evolution of Disulfide Bonds in Proteins." In Protein Folding, 283–300. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1716-8_15.

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Lu, Hsieng S., Michael L. Klein, Richard R. Everett, and Por-Hsiung Lai. "Rapid and Sensitive Determination of Protein Disulfide Bonds." In Proteins, 493–501. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1787-6_50.

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Ovsejevi, Karen, Carmen Manta, and Francisco Batista-Viera. "Reversible Covalent Immobilization of Enzymes via Disulfide Bonds." In Methods in Molecular Biology, 89–116. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-550-7_7.

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Aitken, Alastair, and Michele Learmonth. "Quantitation and Location of Disulfide Bonds in Proteins." In Protein Sequencing Protocols, 399–410. Totowa, NJ: Humana Press, 2003. http://dx.doi.org/10.1385/1-59259-342-9:399.

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Conference papers on the topic "Disulfide bonds"

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Procyk, R., and B. Blomback. "ROLE OF DISULFIDE BONDS NEAR THE CALCIUM BINDING SITES IN FIBRINOGEN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642939.

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Incubation of fibrinogen with 0.5 mM dithiothreitol in the presence of .20 mM calcium chloride cleaved disulfide bonds located at: the N-terminal end of the Aα-chain (either Aα28-Aα28 or Aα45-γ23), the C-terminal end of the Aα-chain (Aα442-Aα472) and the N-terminal end of the γ-chain (either of the symmetrical γ8, γ9 disulfides or the Aα45-γ23 disulfide bond). In the absence of calcium ions two additional disulfides, γ326-γ339, and one in the N-terminal end of the γ-chain were reduced.Plasmin digestion of the reduced fibrinogens in buffers containing calcium chloride produced fragments D and E, except that smaller fragments of D were generated from the fibrinogen in which the γ326-γ339 disulfide bonds were reduced and alkylated. In these samples calcium did not protect the C-terminal end of the γ-chain from extensive digestion.Addition of thrombin to partially reduced and alkylated fibrinogen prepared in the presence of calcium gave a clotting time similar to control unreduced fibrinogen. However, when the γ326-γ339 disulfide bonds and another γ-chain disulfide bond most likely in the N-terminal region were cleaved in reduced fibrinogen prepared in the absence of calcium, the thrombin clotting time was extremely prolonged. Apparently the disulfide bonded structure supported by γ326-γ339 was important both for binding of calcium and also for normal clotting.
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Fuhlendorff, J., I. Clemmensen, and S. Magnusson. "PRIMARY STRUCTURE OF TETRANECTIN. SEQUENCE HOMOLOGY WITH ASIALOGLYCOPROTEIN RECEPTORS AND WITH PROTEOGLYCAN CORE PROTEIN FROM CARTILAGE." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644380.

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Tetranectin (Mr = 68,000) is a tetrameric blood plasma protein, which binds to plasminogen and also to the lysine-binding site of the isolated kringle 4 from plasminogen. Its four polypeptide chains, which are non-covalently bound, each consists of 181 amino acid residues. We have determined the complete amino acid sequence and the disulfide bonds. Each position corresponds to a single amino acid residue except 34 which contains Ala and Ser and 37 which contains Val and Met in equimolar amounts. The three disulfide bonds connect Cys-50 to Cys-60, Cys-77 to Cys-176 and Cys-152 to Cys-168. The sequence of tetranectin was found to be homologous, to an extent indicating common ancestry, with the extracellular part of the asialoglyco-protein receptors and with the C-terminal globular domain of the cartilage proteoglycan core protein. Conserved residues include the six half-cystines of tetranectin. Therefore, we can now propose disulfide bond patterns for the proteins homologous with tetranectin. Supported by NIH-grant HL-16238 (S.M.), the Danish Science and Medical Research Councils, the Danish Cancer Society and NOVO Foundation.
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Wang, Chih-Hsien, Wenlung Chen, P. M. Champion, and L. D. Ziegler. "Raman Characterizing Disulfide Bonds and Secondary Structure of Bovine Serum Albumin." In XXII INTERNATIONAL CONFERENCE ON RAMAN SPECTROSCOPY. AIP, 2010. http://dx.doi.org/10.1063/1.3482550.

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Zheng, Zhuoyuan, Chen Xin, and Yumeng Li. "Numerical Study on the Interfacial Modification Effects of Soy Protein on Poly(Vinylidene Fluoride)." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11694.

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Abstract The application of bio-degradable green materials is a rising global trend during the past decades for the sake of environment protection and sustainable development. Soy protein-based biomaterial is a promising candidate to replace the petroleum-based synthetic materials and was proved to be an effective functional modifier for polymers from our previous studies. Molecular dynamic (MD) simulation is implemented in this study to provide insights in understanding the underlying mechanisms. 11S molecule is chosen as a representative of soy protein, and three different denaturation processes are applied, including heat denaturation at two temperatures and the breaking of disulfide bonds. It is observed that by controlling the denaturation conditions, the hydrophobicity of the protein molecule is manipulated: high temperature denaturation can increase the exposed area of hydrophilic residues; whereas, by breaking the disulfide bonds, the hydrophobic residues of the molecules can be largely exposed. Besides, the mechanisms of using protein as functional modifier to tune the structures of the hydrophobic Poly(vinylidene fluoride) (PVDF) polymer (amorphous and β-crystal phases) are studied. S-S debond protein is found to favor the formation of amorphous PVDF; whereas, high temperature denatured one has stronger interactions with β phase.
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Suzuki, K., J. Nishioka, H. Kusumoto, and Y. Deyashiki. "BINDING SITE OF VITAMIN K-DEPENDENT PROTEIN S ON C4b-BINDING PROTEIN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644637.

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Protein S, a cofactor for activated protein C, reversibly complexes with a regulatory complement component C4b-binding protein (C4bp) in plasma. In plasma of patients with congenital protein S deficiency, most protein S exists as a complex with C4bp, which has no cofactor activity. C4bp (Mw 550,000) is composed of approximately seven subunits with Mw 75,000 which are linked by disulfide bonds near the carboxy1-terminus. We report here about the complex formation between protein S and C4bp particularly on the binding site of protein S on C4bp molecule. Protein S and C4bp were purified from human plasma. Seventeen mouse monoclonal antibodies against C4bp were prepared. Chymotrypsin-digested C4bp was separated on gel filtration into a fragment with Mw 160,000 derived from the carboxyl-terminal core of the intact C4bp and fragments with Mw 48,000 from the amino-terminus. The carboxy1-terminal fragment with Mw 160,000 was found to be composed of approximately seven polypeptides with Mw 25,000, which were linked by disulfide bonds.The experiments using these fragments and the monoclonal antibodies showed that: (1) Protein S bound not only to the intact C4bp, but also to the fragment with Mw 160,000. (2) The fragment with Mw 160,000 inhibited the binding of protein S to C4bp, but the fragment with Mw 48,000 did not. (3) One of the seventeen monoclonal antibodies blocked the inhibition of C4bp on the cofactor activity of protein S. (4) This antibody inhibited C4bp binding to protein S. (5) The antibody bound to the fragment with Mw 160,000. Based on these results, protein S was suggested to lose its cofactor activity for activated protein C by binding to the carboxyl-terminal core of C4bp where seven subunits are linked by disulfide bonds.
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Belinskaia, D. A., A. A. Batalova, and N. V. Goncharov. "Effect of Intramolecular Disulfide Bonds of Bovine Serum Albumin on Its Binding and Pseudo-Esterase Activity According To Computer Modeling Data." In Mathematical Biology and Bioinformatics. Pushchino: IMPB RAS - Branch of KIAM RAS, 2020. http://dx.doi.org/10.17537/icmbb20.4.

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Roterman, Irena, Mateusz Banach, Leszek Konieczny, and Barbara Kalinowska. "Divergence entropy to characterize the stability in selected enzymes – The role of disulfide bonds in respect to the structure of hydrophobic core." In 2nd International Electronic Conference on Entropy and Its Applications. Basel, Switzerland: MDPI, 2015. http://dx.doi.org/10.3390/ecea-2-b009.

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Taki, M., K. Sato, Y. Ikeda, M. Yamamoto, and K. Watanabe. "THE FUNCTIONAL DOMAIN OF PLATELET MEMBRANE GLYCOPROTEIN lb FOR VON WILLEBRAND FACTOR AND THROMBIN-BINDING." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643512.

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In this paper, we have examined the functional domain of platelet membrane glycoprotein lb (GPIb) by using elastase and a monoclonal antibody against GPIb which specific inhibits both von Willebrand factor (vWF) and thrombin interaction with platelets. Elastase was purified from human granulocytes by using affinity column chromatography according to the method of Okada et al.. A monoclonal antibody against platelet membrane GPIb (56-2) which inhibits both vWF and thrombin-binding to platelets was used for this study. Platelet surface glycoproteins were labelled with 3H by the method of Nurden et al.. Purified GPIb was obtained by a modification of the method of Coller et al. and labelled with 125I using chloramine-T method. Either 3H-labelled platelets or 125I-labelled GPIb was treated with elastase for various time periods. Elastase-treated l25I-GPIb was subjected to immunoaffinity chromatography using 56-2 antibody to determine the functional site of GPIb. Elastase inhibited platelet aggregation or 5-HT release by thrombin, ristocetin-induced platelet agglutination and vWF-binding to platelets in the presence of ristocetin in a dose- and time dependent manner. A fluorogram of SDS-PAGE of 3H-labelled platelets treated with elastase revealed that GPIb band was reduced gradually, and fragments with MW of 97, 70, 60, 47, 44, 37, 25 and 15 KD were released from the platelets. The 47 KD fragment was initially cleaved from the platelets, and subsequently other fragments were digested. Similar results were obtained when purified 125I-GPIb was digested by elastase. When the fragments from purified 125I-GPIb were reacted with 56-2 antibody, only three fragments with MW of 47, 44 and 25 KD were immunoisolated. The electrophoretic mobility of all these three bands was altered under reduced conditions, indicating that all these fragments contain disulfide bonds in their molecules. The 25 KD band showed a much fainter in 3H-labelling than in 125I-labelling.These results suggest that the functional domains of GPIb for both vWF and thrombin-binding may be located in a less glycosylated fragment with a MW of 25 KD on the distal portion of the GPIb molecule, which should contain at least one intramolecular disulfide bond.
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Nowis, Dominika, Justyna Chlebowska, Pawel Gaj, Michal Lazniewski, Malgorzata Firczuk, Karolina Furs, Radoslaw Sadowski, et al. "Abstract 5347: SK053, a small molecule inhibitor of enzymes involved in allosteric disulfide bonds formation, shows potent anti-leukemic effects and induces differentiation of human AML cells." In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-5347.

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Dahiback, Bjorn, Ake Lundwall, Andreas Hillarp, Johan Malm, and Johan Stenflo. "STRUCTURE AND FUNCTION OF VITAMIN K-DEPENDENT PROTEIN S, a cofactor to activated protein C which also interacts with the complement protein C4b-binding protein." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642960.

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Protein S is a single chain (Mr 75.000) plasma protein. It is a cofactor to activated protein C (APC) in the regulation of coagulation factors Va and Villa. It has high affinity for negatively charged phospolipids and it forms a 1:1 complex with APC on phospholipid surfaces, platelets and on endothelial cells. Patients with heterozygous protein S deficiency have a high incidence of thrombosis. Protein S is cleaved by thrombin, which leads to a loss of calcium binding sites and of APC cofactor activity. Protein S has two to three high affinity (KD 20uM) calcium binding sites - unrelated to the Gla-region - that are unaffected by the thrombin cleavage. In human plasma protein S (25 mg/liter) circulates in two forms; free (approx. 40%) and in a 1:1 noncovalent complex (KD 1× 10-7M) with the complement protein C4b-binding protein (C4BP). C4BP (Mr 570.000) is composed of seven identical 70 kDa subunits that are linked by disulfide bonds. When visualized by electron microscopy, C4BP has a spiderlike structure with the single protein S binding site located close to the central core and one C4b-binding site on each of the seven tentacles. When bound to C4BP, protein S looses its APC cofactor activity, whereas the function-of C4BP is not directly affected by the protein S binding. Chymotrypsin cleaves each of the seven C4BP subunits close to the central core which results in the liberation of multiple 48 kDa “tentacte” fragments and the formation of a 160 kDa central core fragment. We have successfully isolated a 160 kDa central core fragment with essentially intact protein S binding ability.The primary structure of both bovine and human protein S has been determined and found to contain 635 and 634 amino acids, respectively, with 82 % homology to each other. Four different regions were distinguished; the N-terminal Gla-domain (position 1-45) was followed by a region which has two thrombin-sensitive bonds positioned within a disulfide loop. Position 76 to 244 was occupied by four repeats homologous to the epidermal growth factor (EGF) precursor. In the first EGF-domain a modified aspartic acid was identified at position 95, B-hydroxaspartic acid (Hya), and in corresponding positions in the three following EGF-domains (positions 136,178 and 217) we found B-hydroxyasparagine (Hyn). Hyn has not previously been identified in proteins. The C-terminal half of protein S (from position 245) shows no homology to the serine proteases but instead to human Sexual Hormon Binding Globulin (SHBG)(see separate abstract). To study the structure-function relationship we made eighteen monoclonal antibodies to human protein S. The effects of the monoclonals on the C4BP-protein S interaction and on the APC cofactor activity were analysed. Eight of the antibodies were calciumdependent, four of these were against the Gla-domain, two against the thrombin sensitive portion and two against the region bearing the high affinity calcium binding sites. Three of the monoclonals were dependent on the presence of chelating agents, EDTA or EGTA, and were probably directed against the high affinity calcium binding region. Three other monoclonals inhibited the protein S-C4BP interaction. At present, efforts are made to localize the epitopes to gain information about functionally important regions of protein S.
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Reports on the topic "Disulfide bonds"

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Chaudhuri, Asish R. Beta III Tubulin, Disulfide Bonds and Drug Resistance: A Novel Approach to the Treatment of Breast Cancer. Fort Belvoir, VA: Defense Technical Information Center, June 2003. http://dx.doi.org/10.21236/ada418572.

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Chaudhuri, Asish R. B III Tubulin Disulfide Bonds and Drug Resistance: A Novel Approach to the Treatment of Breast Cancer. Fort Belvoir, VA: Defense Technical Information Center, June 2004. http://dx.doi.org/10.21236/ada427438.

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Anderson, Olin, and Gad Galili. Development of Assay Systems for Bioengineering Proteins that Affect Dough Quality and Wheat Utilization. United States Department of Agriculture, 1994. http://dx.doi.org/10.32747/1994.7568781.bard.

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The quality and utilization of wheat is largely dependent upon the exact physical/chemical properties of the doughs made from flour/water mixtures. Among the wheat seed components most correlated with dough visoelastic parameters are the high-molecular-weight (HMW) glutenin subunits whose disulfide cross-linked macropolymer is critical for dough functionality. We have used the tools of molecular biology, wheat transformation, heterologous expression of HMW-glutenin subunits in bacteria, and dough micro-mixing experiments to examine some of the molecular basis of HMW-glutenin functionality. In addition, we have developed sets of modified and synthetic gene constructs and transgenic wheat lines that will allow further examination of the role of the HMW-glutenins. Among the results from this work is evidence that the HMW-glutenin repeat domain is directly related to dough properties, the demonstration that interaction between subunits is dependent upon domain presence but not order, a novel understanding of the restrictions on intra-vs inter-chain disulfide bonds, the demonstration that HMW-glutenin genes can be transformed into wheat for simultaneously high expression of the transgene and suppression of the endogenous genes, and the construction of a set of modified HMW-glutenins capable of being epitope tagged for studying polypeptide subcellular processing and the fate of HMW-glutenins in dough mixing experiments.
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Venedicto, Melissa, and Cheng-Yu Lai. Facilitated Release of Doxorubicin from Biodegradable Mesoporous Silica Nanoparticles. Florida International University, October 2021. http://dx.doi.org/10.25148/mmeurs.009774.

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Cervical cancer is one of the most common causes of cancer death for women in the United States. The current treatment with chemotherapy drugs has significant side effects and may cause harm to healthy cells rather than cancer cells. In order to combat the potential side effects, nanoparticles composed of mesoporous silica were created to house the chemotherapy drug doxorubicin (DOX). The silica network contains the drug, and a pH study was conducted to determine the conditions for the nanoparticle to disperse the drug. The introduction of disulfide bonds within the nanoparticle created a framework to efficiently release 97% of DOX in acidic environments and 40% release in neutral environments. The denotation of acidic versus neutral environments was important as cancer cells are typically acidic. The chemistry was proved with the incubation of the loaded nanoparticle into HeLa cells for a cytotoxicity report and confocal imaging. The use of the framework for the anticancer drug was shown to be effective for the killing of cancerous cells.
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Christopher, David A., and Avihai Danon. Plant Adaptation to Light Stress: Genetic Regulatory Mechanisms. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586534.bard.

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Original Objectives: 1. Purify and biochemically characterize RB60 orthologs in higher plant chloroplasts; 2. Clone the gene(s) encoding plant RB60 orthologs and determine their structure and expression; 3. Manipulate the expression of RB60; 4. Assay the effects of altered RB60 expression on thylakoid biogenesis and photosynthetic function in plants exposed to different light conditions. In addition, we also examined the gene structure and expression of RB60 orthologs in the non-vascular plant, Physcomitrella patens and cloned the poly(A)-binding protein orthologue (43 kDa RB47-like protein). This protein is believed to a partner that interacts with RB60 to bind to the psbA5' UTR. Thus, to obtain a comprehensive view of RB60 function requires analysis of its biochemical partners such as RB43. Background & Achievements: High levels of sunlight reduce photosynthesis in plants by damaging the photo system II reaction center (PSII) subunits, such as D1 (encoded by the chloroplast tpsbAgene). When the rate of D1 synthesis is less than the rate of photo damage, photo inhibition occurs and plant growth is decreased. Plants use light-activated translation and enhanced psbAmRNA stability to maintain D1 synthesis and replace the photo damaged 01. Despite the importance to photosynthetic capacity, these mechanisms are poorly understood in plants. One intriguing model derived from the algal chloroplast system, Chlamydomonas, implicates the role of three proteins (RB60, RB47, RB38) that bind to the psbAmRNA 5' untranslated leader (5' UTR) in the light to activate translation or enhance mRNA stability. RB60 is the key enzyme, protein D1sulfide isomerase (Pill), that regulates the psbA-RN :Binding proteins (RB's) by way of light-mediated redox potentials generated by the photosystems. However, proteins with these functions have not been described from higher plants. We provided compelling evidence for the existence of RB60, RB47 and RB38 orthologs in the vascular plant, Arabidopsis. Using gel mobility shift, Rnase protection and UV-crosslinking assays, we have shown that a dithiol redox mechanism which resembles a Pill (RB60) activity regulates the interaction of 43- and 30-kDa proteins with a thermolabile stem-loop in the 5' UTR of the psbAmRNA from Arabidopsis. We discovered, in Arabidopsis, the PD1 gene family consists of II members that differ in polypeptide length from 361 to 566 amino acids, presence of signal peptides, KDEL motifs, and the number and positions of thioredoxin domains. PD1's catalyze the reversible formation an disomerization of disulfide bonds necessary for the proper folding, assembly, activity, and secretion of numerous enzymes and structural proteins. PD1's have also evolved novel cellular redox functions, as single enzymes and as subunits of protein complexes in organelles. We provide evidence that at least one Pill is localized to the chloroplast. We have used PDI-specific polyclonal and monoclonal antisera to characterize the PD1 (55 kDa) in the chloroplast that is unevenly distributed between the stroma and pellet (containing membranes, DNA, polysomes, starch), being three-fold more abundant in the pellet phase. PD1-55 levels increase with light intensity and it assembles into a high molecular weight complex of ~230 kDa as determined on native blue gels. In vitro translation of all 11 different Pill's followed by microsomal membrane processing reactions were used to differentiate among PD1's localized in the endoplasmic reticulum or other organelles. These results will provide.1e insights into redox regulatory mechanisms involved in adaptation of the photosynthetic apparatus to light stress. Elucidating the genetic mechanisms and factors regulating chloroplast photosynthetic genes is important for developing strategies to improve photosynthetic efficiency, crop productivity and adaptation to high light environments.
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